1. Field of the Invention
This invention relates to laminates and foam filled sheet products, both decorative and structural, and more particularly it relates to structurally rigid sheets of foam having glass fiber reinforcement, which are particularly useful in thermal insulating applications. It also relates to a method for forming such a product.
2. Description of the Prior Art
Foam products have been reinforced in various ways to give them added strength or other desirable physical properties which the foam itself is incapable of providing. These foam products have become increasingly useful in the building industry since they possess many properties which make them extremely valuable in this field. They have high structural strength coupled with relatively low density and thus are particularly well suited for use as core materials in sandwich type structural laminates. Furthermore, the rigid foam laminates are excellent heat insulators because of their fine closed cell structure. Many different techniques have been developed for manufacturing foam laminates, such as those described in U.S. Pat. Nos. 2,866,730, 3,172,072, 3,554,851, 3,578,544, 3,617,594, 3,627,603, 3,867,494, and 4,118,533.
The last-mentioned of the above patents, i.e., U.S. Pat. No. 4,118,533, discloses a relatively simple method of producing such foam laminates. In this method, a mat of glass fibers is contacted with a foam-forming mixture and the resulting fibrous mat/foamable mixture composite is contacted with a facing sheet(s) and then passed between the nip of two rotating rolls, thereby forcing the foam-forming mixture into the interstices between the glass fibers of the mat. After passing between the nip of the two rolls, the composite is next conveyed into an oven where the foam-forming mixture is permitted to expand and the fibers of the glass fiber mat separate under the influence of the expanding foam to become evenly distributed in the cured foam laminate. Through this simple method it has been possible to continuously manufacture at a high production rate a plastic foam insulation board having superior performance characteristics and a highly pleasing appearance.
Notwithstanding the general high quality of the continuous process of U.S. Pat. No. 4,118,533, it has the disadvantageous feature that the glass fiber mat and facing sheets are each separately fed to the nip of the two rotating metering rolls. Because the separately introduced mat of glass fibers and facers (e.g., thin sheets of aluminum foil) are subjected to variable tensions of considerable magnitude as they are pulled at high speed from their supply rolls toward the metering rolls, it transpires that the continuous operation is marred by drawbacks involving breakage and other damage to the facers and mat, e.g., foil breaks, "necking in" of the glass mat, glass mat splices, etc. The difficulty sometimes necessitates a lengthy shutdown of the production line. These problems result in raw material waste, rejected product, and general operating inefficiencies. It would be highly desirable if a simple and efficient method of continuously producing foamed laminates could be found which incorporates the advantageous features of the method disclosed in U.S. Pat. No. 4,118,533 but avoids to a great extent the above-mentioned disadvantages associated with this method.